In conventional cremation systems, high-temperature exhaust gas generated in a cremation furnace is first cooled by a cooler etc., then it undergoes a dust removal process in a dust collector, followed by the removal of dioxin and the like in a catalytic device, before finally being released through a stack to the atmosphere. That is, it is a common practice in conventional cremation systems to simply throw away the high-temperature thermal energy without reusing it.
In recent years, however, there has been a demand for development of a cremation system which can save energy by increasing the energy efficiency of the cremation system as a whole while respecting the dignity of a person (body).
As a first conventional technology for saving energy, a power generation system and a cremation furnace described in Patent Literature 1 (Japanese Patent Laid-Open No. 2012-13266) are cited. This literature describes how to effectively utilize the thermal energy generated in the cremation furnace by integrating the power generation system in a cremation system, using the high-temperature thermal energy generated in the cremation furnace to generate steam by means of a heat exchanger, and using this steam to drive a steam turbine and generate power.
Next, the first conventional technology will be described in detail with reference to FIG. 10. In FIG. 10, a cremation furnace 101 includes a boiler function. Water supplied by a feed water pump 106 is gasified by the high-temperature heat inside the cremation furnace 101, and water vapor is sent to a steam separator 102. After water droplets are removed from the water vapor by the steam separator 102, steam is sent to a power generator 103 and drives a steam turbine to generate power. The low-pressure steam after serving to drive the steam turbine is sent to a steam condenser 104, to which cooling water is supplied from a cooling tower 105, and is condensed into water and sent to a hot well tank 107 to be circulated to the cremation furnace 101. Thus, the cremation furnace described in this publication enhances the thermal efficiency by turning the incineration furnace into a boiler.
As a second conventional technology concerned with a cremation facility integral with a power generation device, a mobile integral cremation facility described in Patent Literature 2 (Japanese Patent Laid-Open No. 2010-133693) will be described with reference to FIG. 11. In this publication, an electricity supply device 115 supplies power for operating an incineration furnace 111, cooling devices 112a, 112b, dust collectors 113a, 113b, and an exhaust heat discharge device 114. Thus, there is no need for receiving power from the outside, which is why the mobile integral cremation facility can be realized.
As a third conventional technology for power generation through effective utilization of low-temperature, low-volume exhaust heat, an exhaust heat power generation device and a method for controlling the degree of superheat of working medium steam in an exhaust heat power generation device, described in Patent Literature 3 (Japanese Patent No. 4875546), will be described with reference to FIG. 12.
FIG. 12 is a configurational view of the exhaust heat power generation device described in this publication. Warm water from an exhaust heat source 129 is supplied to a steam generator 121 to heat a working medium liquid and generate working medium steam. Then, this working medium steam is supplied to a liquid drop separator 122. The pressure and the temperature of this working medium steam are measured with a pressure sensor 126 and a temperature sensor 127, respectively, and the measurement information is transmitted to a control panel 128. The working medium steam, of which the pressure and the temperature are controlled by the control panel 128, rotates a turbine 123 and drives a high-speed power generator, which is coupled to the turbine, to generate power.
The working medium steam from the turbine 123 is cooled into a liquid in a condenser 124, and is sent to the steam generator 121 through a liquid feed pump 125, so that working medium steam is generated again. Thus, the working medium with a low boiling point (about 40° C.) is circulated. This exhaust heat power generation device calculates the degree of superheat with reference to the pressure and the temperature measured by the pressure sensor 126 and the temperature sensor 127, and controls the flow rate of the working medium liquid by increasing or reducing the rotation speed of the liquid feed pump 125 such that the calculated value matches a preset degree of superheat. As the degree of superheat is kept constant through this manner of control, the exhaust heat is recovered efficiently for power generation.
As a fourth conventional technology for obtaining stable power output regardless of changes in exhaust heat flow rate or exhaust heat temperature, a power generation control device utilizing waste heat described in Patent Literature 4 (Japanese Patent Laid-Open No. H10-184316) will be described with reference to FIG. 13.
FIG. 13 is a block diagram of a power generation plant described in this publication. The power generation plant has a steam flow rate control system for controlling the flow rate of steam flowing into a steam turbine 131, a steam pressure control system for controlling the inlet pressure of the steam turbine, and a hot water level control system for controlling the hot water level in each of steam separators 132a to 132c. The power generation plant further includes a hot water temperature control system for controlling the temperature of excess hot water in each of the high-pressure, intermediate-pressure, and low-pressure steam separators 132a to 132c, a steam condenser level control system for controlling the water level in a steam condenser 133, a makeup water volume control system for controlling the volume of makeup water which is supplied to a cooling tower 134 such that the water level in the cooling tower 134 reaches a set value, and an internal temperature control system for controlling the cooling water temperature in the cooling tower 134. Using these control systems, the power generation plant generates power with high efficiency by stabilizing power load fluctuations, fluctuations in flow rate of steam flowing into the steam turbine, fluctuations in flow rate and pressure of exhaust heat steam, fluctuations in internal temperature of the steam condenser, fluctuations in cooling water volume, fluctuations in outlet temperature of an exhaust heat exchanger, level fluctuations in the cooling tower, etc.
As a fifth conventional technology which improves the efficiency of utilization of heat source energy by means of binary power generation, a binary power generation system described in Patent Literature 5 (Japanese Patent Laid-Open No. 2009-221961) will be described with reference to FIG. 14.
FIG. 14 is a block diagram of the binary power generation system described in this publication. The power generation system generates power by introducing steam of a low-boiling working medium 149, which has evaporated through heat exchange with a heat source fluid 141, into a steam turbine 144. A closed loop is formed by arranging a preheater 143 which preheats a working medium, evaporators 142A, 142B, the steam turbine 144, a heat recovery unit 148, a condenser 146, and medium transfer pumps 147A, 147B in series. In the binary power generation system of this publication, the plurality of stages of evaporators 142A, 142B, which are different from each other in steam temperature and pressure of the working medium, are provided, and the steam generated in these stages is respectively sent to the high-pressure stage and the low-pressure stage of the steam turbine (mixed-pressure turbine) 144 to drive a turbine power generator 145. This configuration enhances the efficiency of utilization of the thermal energy possessed by the heat source fluid, compared with the method of driving a steam turbine with the steam of a working medium generated from a single-stage evaporator.